SLC34A3 encodes NaPi-IIc (NPT2c), a sodium-dependent phosphate cotransporter located in the brush border membrane of renal proximal tubule cells that plays a critical role in phosphate homeostasis 1. The transporter mediates active phosphate reabsorption from urine via Na+ cotransport with a 2:1 stoichiometry, functioning as part of the kidney's mechanism to control systemic phosphate balance 12. Loss-of-function mutations in SLC34A3 cause hereditary hypophosphatemic rickets with hypercalciuria (HHRH), an autosomal recessive disorder characterized by renal phosphate wasting, hypophosphatemia, elevated 1,25(OH)2 vitamin D levels, hypercalciuria, and rickets/osteomalacia 34. Both homozygous and heterozygous carriers show significantly increased risk of kidney stones and nephrocalcinosis, with 46% of biallelic carriers developing these complications compared to 6% in unaffected family members 5. Adult patients with biallelic SLC34A3 variants have a six-fold increased prevalence of chr9 kidney disease compared to the general population 4. The transporter is regulated by phosphaturic hormones including parathyroid hormone and FGF23, and represents a potential therapeutic target for hyperphosphatemia management 12.